1. Field of the Invention
The present invention relates to an image formation method, more concretely to an image formation method using a thermal transfer sheet and a thermal transfer image-receiving sheet.
2. Description of the Related Art
Heretofore, various thermal transfer recording methods are known. Above all, a dye diffusion transfer recording system is specifically noted as a process capable of producing color hard copies of which the image quality is the nearest to that of silver salt photographs. Moreover, as compared with silver salt photographs, the system has other various advantages in that it is a dry system, it can produce visible images directly from digital data, and it is simple in image duplication.
In the dye diffusion transfer recording system, a dye (or colorant)-containing thermal transfer sheet (hereinafter referred to as “ink sheet”) and a thermal transfer image-receiving sheet (hereinafter referred to as “image-receiving sheet”) are put one upon another, and the thermal transfer sheet is heated with a heating element such as thermal head from which the heat generation is controlled by electric signals given thereto, whereby the colorant in the thermal transfer sheet is transferred onto the thermal transfer image-receiving sheet for image information recording thereon. In this, three colors of cyan, magenta and yellow, or four colors of these and black are recorded as superimposed, thereby giving a color image having a continuously changing color density in a mode of transfer recording. Simultaneously with transfer recording of color images, a transferable protective layer laminate (hereinafter referred to as “OP layer”) may be transferred onto the thermal transfer image-receiving sheet to protect the outputted images.
With the recent development of digital imaging technology by computer, the quality of recorded images is bettered and the market of the dye diffusion transfer recording system is expanding, and with that, the print system installation environment is being diversified.
On the other hand, JP-A 2008-6781 discloses a thermal transfer image-receiving sheet in which the receiving layer contains a polymer containing a vinyl chloride-derived recurring unit in some degree, gelatin and a reactive group-having silicone compound and in which the gelatin is hardened with a specific hardener.
JP-A 63-135288 discloses a thermal transfer sheet having a subbing layer that comprises a polymer having an inorganic main chain of an oxide of a Group IVa or IVb element, and a dye layer.
The present inventors have investigated the prior art technology, and have known that the image outputted on the image-receiving sheet of JP-A 2008-6781 in a high-humidity environment is unsatisfactory in point of the transfer density thereof.
The image formation system of transferring the dye from a dye layer onto an image-receiving sheet followed by transferring a transferable protective layer laminate thereon to complete the outputted image is problematic in that the gloss of the image is often uneven when the image is outputted in a high-humidity environment.